Thirty years ago, on a rainy morning in the northwestern Colombian town of Sucre, a 22-year-old student was hacked to death by two machete-wielding brothers who believed he had violated their sister's honor.

Among the medical student's appalled Sucre friends was a young newspaper writer named Gabriel Garcia Marquez. The newspaper writer turned to fiction, and over the years Garcia Marquez's novels and short stories, particularly his stunning family chronicle, "One Hundred Years of Solitude," have made him perhaps Latin America's best-known novelist and one of the most widely read Spanish-language writers in the world.

Last month, in Madrid, Buenos Aires, Mexico City and Bogota, publishers launched the novel that he based on the murder of his friend. The slim paperbound volume, "Cronica de una Muerte Anunciada " ("The Story of an Announced Death"), is being heralded- with a literary extravaganza unlike anything Colombia has ever seen.

Huge billboards trumpet Garcia Marquez's name over the airport highway. Street vendors line that sidewalk outside the downtown movie theaters, selling copies of the novel as fast as they can stack them up. The man who is to translate the novel into Russian has already begun his work (it is unlikely to appear in English until next year). The Bogota newspaper El Espectador, which gave Garcia Marquez his first big-city writing job, made the publication front-page news, ran a large photo of the stacked book cartons, and observed that if every one of the Colombian editions were laid end to end, they would extend for 155 miles.

But Garcia Marquez, a compact, genial, moustached man who is by now the most famous Colombian in the world, is not here to enjoy the celebration. To the embarrassment and exceeding irritation of government officials, he fled Colombia last month, saying he feared both for his own safety and for the future of the country's civilian democracy.

According to Garcia Marquez, who is affectionately known throughout Colombia as "Gabo," his concern began to mount late last March, after the Colombian Army arrested a large group of M19 guerrillas who had sailed from Panama into southwestern Colombia. A wounded 18-year-old among them had publicly declared that he had received training in Cuba, prompting Colombian President Julio Cesar Turbay Ayala to suspend relations with the Cuban government.

"I had been in Havana from Jan. 28 to Feb. 11 for a writer's meeting," Garcia Marquez told a Washington Post correspondent in Mexico, where he is now living. "On Monday of that week," when Colombia suspended relations with Cuba, "I was warned privately that I would be accused by the Army of having been involved in the arms shipment from Panama to Colombia. By Tuesday, a very well-placed source told me the guerrillas were being forced to confess that my trip to Cuba and Panama had been precisely to make the arrangements for them."

When more people passed him warnings, Garcia Marquez said, including one who said he had overheard an Army general at an official dinner predicting the writer's arrest, Garcia Marquez invited himself to supper at the home of his friend, the Mexican ambassador. "I was told there was reason to believe they would fabricate false evidence against me," Garcia Marquez said. "And in keeping with the [security] statutes, I would be held incommunicado for 10 days. Anyway, in Colombia you don't get arrested. You get pulled out of your house at dawn, and they search and mess up your house."

Garcia Marquez spend the night in the Mexican Embassy, and the next day, under the diplomatic protection of the Mexicans, he got on a plane for Mexico City, where he has lived off and on for many years. As Colombian officials protested that there was no arrest order pending, Garcia Marquez tossed out his final departing barb: the Colombian military wielded so much power, he said, that it acted without the knowledge or consent of the civilians who are supposed to run the country.

The scandal was immense. There were those who said Garcia Marquez had let his famous imagination run slightly amok, that the whole thing was a publicity stunt to push his new novel, that in the words of one nasty little joke, "they wouldn't arrest him, so he left."

President Turbay reportedly suggested that Garcia Marquez, who is also well-known for his left-wing politics, was deliberately trying to discredit the Colombian government. Defense minister Luis Carlos Camacho Leyva, an Army general who is often cited as one of the main sources of military power, dismissed Garcia Marquez's charges as nonsense. "The only military force that was looking for Garcia Marquez," Camacho Leyva said, "was a policeman who accompanied him to the airport to ask for his autograph."

But Garcia Marquez is hardly the first well-known Colombian to worry publicly about the growing military control over the government of Colombia, which is one of only five electoral democracies left on the South American continent. In spite of the country's democratic tradition, the military has in recent years been exerting so much influence over civilian affairs that dismayed Colombians now use the word "Uruguayization" -- a reference to the Uruguayan Army's gradual 1973 takeover that ended with a repressive and thoroughly military-controlled Uruguayan government.

"Since 1977, and above all since 1978, the military has been taking a bigger and bigger role in politics," said Alfredo Vasquez Carrizosa, a former foreign minister who has become a well-known human-rights activist. Aded a bitter Colombian journalist, who knows Garcia Marquez well: "In reality, they are running things now. They prefer to run things behind the facase of democracy, where they have less resistance."

The uruguay comparison is particularly apt because the Colombian military is justifying much of its increased power, just as the Uruguayan military did, as necessary in its battle against a highly publicized guerrilla movement. Captured members of the M19 and other guerrilla organizations are being tried to military courts-martial.

Certain rural areas of the country, where guerrilla movement has been reported, are said by critics to be under such extensive military control that the Army has become a virtual local government. And a severe national security law was adopted in 1978 at least partially at the urging of the military. Colombian human-rights organizations have said that brutal interrogations and torture became routine investigatory procedure after the adoption of that law, although a recent, still unreleased report by the Inter-American Human Rights Commission reportedly found no evidence of systematic torture of prisoners.

The nervousness about creeping militarism recently has become such that an editorial in the bimonthly Army magazine got extensive press coverage and an angry rebuttal from the president. When Gen. Fernando Landazabal Reyes wrote in the magazine, with tantalizing ambiguity, that "subversion will go on as long as we fail to change the social, political, and economic fields," some Colombians read his words as a not-so-veiled coup threat.

Turbay immediately canceled a planned visit to China and the Soviet Union and retorted in a press conference, "There is no country in the world that is not affected by terrorism. If one accepted the thesis that social problems justify subversion, we would find two-thirds of the world having to raise arms against their legitimate governments."

"The problem is that nobody's sure of not being detained," said Vasquez Carrizosa. "The fact that they said they were going to interrogate Garcia Marquez was enough to make him seek protection in Mexico. This is evidence of the psychological unease that we are feeling. If Garcia Marquez has this fear, what must be the reaction of a worker who doesn't have the fame or the resources of Garcia Marquez?"

Turbay, who is sometimes portrayed as a man working furiously to keep both the guerrilla movements and the military at bay, said in an interview that the fears of militarization were "another product of the imagination of the noelist Garcia Marquez. Here there is unity of government. We are the oldest democracy in Latin America. . . . This is as full a democracy as America's, or the most advanced European nations'."

Turbay still insists there was never any order for Garcia Marquez's arrest."When a case concerns a person of Garcia Marquez's fame, it is natural that the president of the republic should be informed," he said. "I was not informed in any way about this decision -- which did not exist, except in the mind of the writer Garcia Marquez."

Whether the military was actually preparing to detain and interrogate Garcia Marquez is still a subject of considerable debate in Colombia. "I think this was some bad gossip," said Enrique Alvarado, managing editor of El Espectador, who has known Garcia Marquez since the young writer, then thin and slightly stunned by his transition from the coastal area where he grew up, first began writing eloquent articles for the newspaper. "I don't believe the military was going to do it. . . . But if I put myself in his place, I would have been afraid too."

Alvarado fairly snorted at the notion that Garcia Marquez would have staged the whole thing for publicity. "That's as though Hemingway were alive and trying to look for publicity by hanging one-handed from a tall building," he said. "Garcia Marquez doesn't need it. "One Hundred Years of Solitude' has given him immortality. Whatever he writes now is a success -- in the case of his new book, there are already a million copies sold."